Digital Camera Patent Abstract
A digital camera includes a processor having an algorithm for comparing
a set of resolution pixel values in a generated image file with
corresponding ones of resolution pixel values in a user selected
file and for providing as a final digital zoom image resolution
the set of resolution pixel values in the generated image file when
the corresponding ones of the resolution pixel values in the user
selected file are at least equal but not less than the corresponding
resolution pixel values in the generated image file, and a scaled
down set of resolution pixel values when the corresponding ones
of the resolution pixel values in the user selected file are less
than the corresponding resolution pixel values in the generated
image file. Digital Camera Patent Claims
I claim:
1. A method of maximizing image resolution in a digital camera,
comprising: applying a user selected digital zoom factor Z.sub.f
to a highest available image resolution value to obtain a maximum
image file size; applying a user selected image file size to a digitally
zoomed image when said maximum image file size is at least equal
to but not greater than said user selected image file size; and
applying a resized image file size to said digitally zoom image
when said maximum image file size is greater than said user selected
image file size, wherein said resized image file size is scaled
down file size.
2. A method of maximizing image resolution in a digital camera
according to claim 1, wherein said user selected digital zoom factor
Z.sub.f includes at least two digital zoom factors.
3. A method of maximizing image resolution in a digital camera
according to claim 2, wherein one of said at least two digital zoom
factors is Z.sub.f1 and wherein the other one of said at least two
digital zoom factors is Z.sub.f2.
4. A method of maximizing image resolution in a digital camera
according to claim 3, wherein Z.sub.f1 is a 1.5.times. zoom factor
and wherein Z.sub.f2 is a 2.0.times. zoom factor.
5. A method of maximizing image resolution in a digital camera
according to claim 1, wherein said highest available image resolution
value is N.sub.max pixels by M.sub.max pixels.
6. A method of maximizing image resolution in a digital camera
according to claim 5, wherein said highest available image resolution
value is 1600 pixels by 1200 pixels.
7. A method of maximizing image resolution in a digital camera
according to claim 6, wherein said maximum image file size is N.sub.max
/Z.sub.f pixels by M.sub.max /Z.sub.f pixels.
8. A method of maximizing image resolution in a digital camera
according to claim 7, wherein said maximum image file size is 1066
pixels by 800 pixels when Z.sub.f is a 1.5.times. zoom factor.
9. A method of maximizing image resolution in a digital camera
according to claim 7, wherein said maximum image file size is 800
pixels by 600 pixels when Z.sub.f is a 2.0.times. zoom factor.
10. A method of maximizing image resolution in a digital camera,
comprising: applying a user selected digital zoom factor Z.sub.f
to a highest available image resolution value of N.sub.max pixels
by M.sub.max pixels to obtain a maximum image file size of N.sub.max
/Z.sub.f pixels by M.sub.max /Z.sub.f pixels; applying a user selected
image file size of N.sub.sn pixels by M.sub.rn pixels to a Z.sub.f
digitally zoomed image when said maximum image file size is at least
equal to but not greater than said user selected image file size;
and applying a resized image file size to said Z.sub.f digitally
zoom image when said maximum image file size is greater than said
user selected image file size, wherein said resized image file size
is scaled down file size.
11. A method of maximizing image resolution in a digital camera
according to claim 10, wherein said scaled down file size is [(N.sub.max
/Z.sub.f pixels divided by N.sub.sn pixels) pixels divided into
N.sub.max /Z.sub.f pixels] by [(M.sub.max /Z.sub.f pixels divided
by M.sub.rn pixels) pixels divided into M.sub.max /Z.sub.f pixels].
12. A method of maximizing image resolution in a digital camera
according to claim 10, wherein said step of applying a user selected
digital zoom factor Z.sub.f includes: receiving a zoom selection
signal indicative of said user selected digital zoom factor Z.sub.f
; and storing said user selected digital zoom factor Z.sub.f.
13. A digital camera, comprising: means for applying a user selected
digital zoom factor Z.sub.f to a highest available image resolution
value to obtain a maximum image file size; means for applying a
user selected image file size to a digitally zoomed image when said
maximum image file size is at least equal to but not greater than
said user selected image file size; and means for applying a resized
image file size to said digitally zoom image when said maximum image
file size is greater than said user selected image file size, wherein
said resized image file size is scaled down file size.
14. A method of providing a final digital zoom image resolution,
comprising: comparing a set of resolution pixel values in a generated
image file with corresponding ones of resolution pixel values in
a user selected file; providing as the final digital zoom image
resolution said set of resolution pixel values in the generated
image file when the corresponding ones of the resolution pixel values
in the user selected file are at least equal but not less than the
corresponding resolution pixel values in said generated image file;
and providing as the final digital zoom image resolution a scaled
down set of resolution pixel values when the corresponding ones
of the resolution pixel values in the user selected file are less
than the corresponding resolution pixel values in said generated
image file.
15. A digital camera, comprising: a processor having an algorithm
for comparing a set of resolution pixel values in a generated image
file with corresponding ones of resolution pixel values in a user
selected file and for providing as a final digital zoom image resolution:
said set of resolution pixel values in the generated image file
when the corresponding ones of the resolution pixel values in the
user selected file are at least equal but not less than the corresponding
resolution pixel values in said generated image file, and a scaled
down set of resolution pixel values when the corresponding ones
of the resolution pixel values in the user selected file are less
than the corresponding resolution pixel values in said generated
image file.
16. A digital camera according to claim 15, wherein said algorithm
includes the following steps: applying a user selected digital zoom
factor Z.sub.f to a highest available image resolution value of
N.sub.max pixels by M.sub.max pixels to obtain a maximum image file
size of N.sub.max /Z.sub.f pixels by M.sub.max /Z.sub.f pixels;
applying a user selected image file size of N.sub.sn pixels by M.sub.rn
pixels to a Z.sub.f digitally zoomed image when said maximum image
file size is at least equal to but not greater than said user selected
image file size; and applying a resized image file size to said
Z.sub.f digitally zoom image when said maximum image file size is
greater than said user selected image file size, wherein said resized
image file size is scaled down file size.
17. A digital camera according to claim 15, wherein said algorithm
includes the following steps: comparing the set of resolution pixel
values in said generated image file with corresponding ones of resolution
pixel values in said user selected file; providing as the final
digital zoom image resolution said set of resolution pixel values
in the generated image file when the corresponding ones of the resolution
pixel values in the user selected file are at least equal but not
less than the corresponding resolution pixel values in said generated
image file; and providing as the final digital zoom image resolution
said scaled down set of resolution pixel values when the corresponding
ones of the resolution pixel values in the user selected file are
less than the corresponding resolution pixel values in said generated
image file.
18. A digital camera, comprising: a modifier circuit for applying
a user selected digital zoom factor Z.sub.f to a highest available
camera image resolution value to obtain a maximum image file size;
and a comparison circuit for applying a user selected image file
size to a digitally zoomed image when said maximum image file size
is at least equal to but not greater than said user selected image
file size, and for applying a resized image file size to said digitally
zoom image when said maximum image file size is greater than said
user selected image file size, wherein said resized image file size
is scaled down file size.
Digital Camera Patent Description
FIELD OF INVENTION
The present invention relates generally to cameras, and more particularly,
to a digital camera having a digital zoom feature with a maximizing
image resolution algorithm for improved image quality.
BACKGROUND OF THE INVENTION
In general, both digital and analog cameras must give feedback
to a user of what area of a scene to be photographed will be captured
when a picture is taken. This has traditionally been accomplished
using a built-in device called an optical viewfinder--an optical
window that enables the user to visualize the scene and see exactly
what area of the scene that will be captured by the camera lens
system.
In order to change the area to be captured by the camera lens system,
many digital and analog cameras also include what is commonly called
a zoom feature. The zoom feature is limited to optical zooming in
the analog camera but may include both optical zooming and digital
zooming in a digital camera.
Before discussing the merits of optical and digital zooming, it
may be beneficial to briefly review the difference between what
is known in the state of the art as a through the lens (TTL) camera
and a point and shoot (PAS) camera.
In the TTL camera, as a user views a scene to be photographed he
or she utilizes the camera viewfinder. More particularly, the user
is viewing the scene through the lens system of the camera. That
is, with the help of an internally positioned mirror within the
TTL camera, the light passing through the lens system is reflected
by the internal mirror and directed to the optical viewfinder for
consideration by the user. When the user is satisfied with the scene
to be captured, the mirror is repositioned allowing a direct light
path to the photosensitive plane of the camera, and thus, allowing
the scene to be captured as viewed through the optical viewfinder.
The PAS camera is much less expensive and does not allow the user
to view the scene through the primary lens system. Instead, the
optical viewfinder is provided with a secondary lens system that
moves in and out in tandem with the primary lens system. In short
then, in the PSA camera two separate light paths are established;
one light path for the primary lens system to the photosensitive
plane of the camera and another light path through the secondary
lens system to the viewfinder for the scene preview benefit of the
user.
Considering now the merits of the two types of zooming, optical
zooming and digital zooming, it will be understood by those skilled
in the art that optical zooming is a mechanical operation that affects
movement of the primary lens system so as to enlarge or reduce a
viewed object. Thus, for example, by moving the primary lens system
a user may, in a smooth mechanical transition, view a group arrangement
of flowers down to a single flower within the group and then back
to the entire arrangement. This transition is commonly called "zooming
in" and "zooming out" of the scene.
With the advent of digital cameras and photography, two new developments
emerged: imaging view display modules, known as liquid crystal display
(LCD) units and digital zooming. With the LCD unit, a user is able
to independently view the scene both before the image is captured,
in a preview mode of operation, and after the image has been captured
and stored, in a post-view or review mode of operation. In short
then, the preview mode of operation is essentially the same mode
of operation found in a TTL type of camera as the image displayed
on the LCD is taken directly from the photosensitive plane of the
digital camera that is otherwise called a charged couple device
(CCD).
Digital zooming is an electrical manipulation that selects a portion
of the image converted by the CCD so that the selected portion appears
to be enlarged when viewed on the whole viewing area of the LCD.
From the foregoing, it will be understood by those skilled in the
art that the same effects of optical zooming can be achieved and
viewed on the LCD without having to incur the high costs associated
with providing a moving primary lens system. The trade off for such
a benefit however, is degradation in the image quality as viewed
on the LCD as the CCD utilizes fewer pixel locations.
In certain high-end digital cameras, the degradation in image quality
brought about by digital zooming is overcome by providing a conventional
optical zooming feature. In this type of camera, the viewfinder
tracks the camera lens to enable the user to visually see the effects
of the optical zooming. Alternatively, the user may also view the
effects of the optical zooming on the LCD in the preview mode of
operation as the magnification is achieved by the primary lens system
prior to the object image being converted by the CCD. In most situations
however, the user will not utilize the LCD for the purpose of observing
optical zooming as LCD use places a high electrical drain on the
battery system of the camera.
Recently, certain digital cameras have been offered providing both
optical and digital zooming. In such cameras, the user is able to
select which one of the effects is desired to arrive at a desired
magnification. Thus, for example to arrive at a 4.times.-magnification
factor a user could select a 2.times. optical effect and a 2.times.
digital effect.
While such combined effects are desirable in the preview mode of
operation, the combined zooming effect has been less than desirable
due to the high electrical drain on the camera battery system. That
is as the user gets the "what you see is what you get"
view of image data only by viewing the LCD image there is a constant
power drain when the combined zoom effect is in operation.
From the foregoing, it should be understood that when the LCD is
powered off, the user is limited to viewing only the optical zooming
effects through the viewfinder. In this regard, in prior art digital
camera with combined zoom features, the optical zoom is always enabled
while the digital zoom is only enabled when the LCD is in a powered
up state of operation. In this manner, the user would never be in
a situation of guessing at what exactly is included in the scene
to be captured.
While the above discussed cameras and methods of operation provide
the combined effects of both optical and digital zooming, the effects
of the digital zooming significantly reduce the useful operating
period of the camera relative to the available battery power source.
In other words, with a combined optical and digital zooming feature
camera, the costs of operating the camera are significantly higher
as expensive batteries must be replaced on a much more frequent
basis.
Therefore it would be highly desirable to have a new and improved
digital camera that is easy to use providing continuous coverage
with maximum image quality for any magnification.
DISCLOSURE OF THE INVENTION
In accordance with the present invention, a new and improved digital
camera includes a processor having an algorithm for comparing a
set of resolution pixel values in a generated image file with corresponding
ones of resolution pixel values in a user selected file and for
providing as a final digital zoom image resolution the set of resolution
pixel values in the generated image file when the corresponding
ones of the resolution pixel values in the user selected file are
at least equal but not less than the corresponding resolution pixel
values in the generated image file, and a scaled down set of resolution
pixel values when the corresponding ones of the resolution pixel
values in the user selected file are less than the corresponding
resolution pixel values in the generated image file.
BRIEF DESCRIPTION OF DRAWINGS
The above mentioned features of the present invention and the manner
of attaining them will become apparent and the invention itself
will be best understood by reference to the following description
of the preferred embodiment of the invention, in conjunction with
the accompanying drawings, wherein:
FIG. 1 is a block diagrammatic representation of a digital camera
that is constructed in accordance with the preferred embodiment
of the present invention;
FIG. 2 is a block diagram of the digital camera of FIG. 1 illustrating
its use with a data processing system;
FIG. 3 is a high-level zoom control flow chart illustrating the
operational steps of the digital camera of FIG. 1;
FIG. 4 is a high-level aperture setting flow chart illustrating
the operational steps of the digital camera of FIG. 1;
FIG. 5 is a high-level fixed focus mode flow chart illustrating
the operational steps of the digital camera of FIG. 1;
FIG. 6 is a graphical representation of a prior art digital zoom
and optical zoom range in a two-control button system;
FIG. 7 is a graphical representation of another prior art digital
zoom and optical zoom range in a three or four-control button system;
FIG. 8 is a graphical representation of the digital and optical
zoom range of the present invention illustrating the smoothing transition
over the entire range in a two-control button system;
FIG. 9 is a diagrammatic representation of a front face view of
an aperture lens arrangement within the digital camera of FIG. 1;
FIG. 10 is a graphical representation of admitted light intensity
vs. lens movement within the digital camera of FIG. 1;
FIG. 11 is a high-level auto focus mode flow chart illustrating
the operational steps of the digital camera of FIG. 1;
FIG. 12 is a high-level zoom control algorithm implemented in the
digital camera of FIG. 1;
FIG. 13 is a block diagrammatic representation of another digital
camera that is constructed in accordance with the preferred embodiment
of the present invention; and
FIG. 14 is a high-level flow chart illustrating the enhanced digital
zoom control steps of the digital camera of FIG. 13.
BEST MODE FOR CARRYING OUT THE INVENTION
Referring now to the drawings and more particularly to FIGS, 1-2,
there is illustrated a digital camera system 8 which is constructed
in accordance with the present invention. The digital camera system
8 captures and processes digital images for permanent or temporary
view by a user.
Considering now the digital camera system 8 in greater detail with
reference to FIGS. 1-2, the digital camera system 8 generally includes
a data processing and printing system 9 for receiving and processing
image data, and a digital camera 10 for capturing and storing the
image data to be processed by the system 9. The data processing
and printing system 9 can be configured in various hardware and
software configurations that facilitates digital image processing
such as a personal computer system having a processor or computer,
a monitor, a digital card reader and a printer or a stand alone
photo-printer having an IR port, a digital card reader and an internal
micro-processor that permits image data received on a storage card
module 54 or transmitted on an infrared wavelength via an IR communication
channel, such as an IR channel indicated generally at 75 ( FIG.
2).
In operation, the user utilizing the digital camera 10, selects
a scene to be photographed and frames and focuses the image using
the various camera controls that will be described hereinafter in
greater detail so that the object scene can be captured and stored
when the camera 10 is activated. Once the image has been captured
and stored by the camera 10, the user can select the image either
by itself or with other images that have been previously captured
and stored to cause them to either be transmitted to the processing
system 9 via the IR channel 75 or copy them to the storage card
module 54 with various instruction commands such as how many of
prints of each image are to be prepared, cropping instructions,
rotating instruction, thumbnail instructions and the like. The storage
card module 54 can then be removed from the camera 10 and inserted
in the data processing and printing system digital card reader for
processing purposes. More particularly, the image information and
instructions when received by the processing system 9 are acted
upon resulting in the preparation of image prints in accordance
with the instructions of the user as entered via the camera 10.
Referring now to the drawings and more particularly to FIG. 1,
there is shown in diagrammatic representation the digital camera
10, which is, constructed in accordance with the present invention.
The camera 10 is configured for use with the image processing system
9 to facilitate the review, formatting and printing of high quality
digital photographs. In the preferred embodiment of the present
invention, the camera 10 includes both optical and digital zooming
features as well as a fixed focus feature and an automatic focus
feature, each of which will be described hereinafter in greater
detail when the operation of the camera 10 is described.
The fixed focus mode of operation is also aperture sensitive, allowing
the camera 10 to default to the fixed focus mode of operation. In
the fixed focus mode of operation, the camera 10 automatically adjusts
its focal point and aperture setting relative to the amount of ambient
light being received by the camera 10.
Considering the camera 10 in greater detail with reference to FIG.
1, the camera 10 generally includes a housing 16 having mounted
therein a aperture/lens system or arrangement 13 that facilitates
the zooming feature, aperture setting for light adjustments and
the focusing features for image reproduction purposes. In this regard,
the aperture/lens arrangement 13 generally includes a primary lens
system indicated generally at 14 for focusing and optical zooming
in and out of a scene to be captured, a shutter 19 for allowing
the light indicative of the object to be captured to enter the photosensitive
plane of the camera and an aperture 18 that is automatically adjusted
for receiving the proper amount of light to assure proper image
formation.
In order to allow the user to preview the scene to be captured,
the camera 10 also includes a microprocessor 25 and liquid crystal
display (LCD) unit 38 that are coupled electrically to a charged
coupled device or CCD 15. The LCD unit 38 permits the user to visualize
various message indications relative to camera control as well as
previewing the effects of both optical and digital zooming before
an image is captured. The CCD 15 is disposed in the primary light
path for converting light to an electrical signal that is ultimately
processed by the microprocessor 25 as will be explained hereinafter
in greater detail. As best seen in FIG. 1, the primary light path
extends from the aperture 18 to the charged couple device 15 via
the primary lens system 14 and the shutter 19.
The microprocessor 25 and LCD unit 38 operate to provide one preview
mode of operation that is substantially the same mode of operation
as found in a through the lens (TTL) digital camera. That is, the
user via the LCD unit 38 can view the effects of both optical zooming
and digital zooming when the LCD unit 38 is placed in a power on
condition. It will be appreciated however, by those skilled in the
art, that in this LCD preview mode of operation, the LCD unit 38
places a significant battery drain on the electrical system of the
camera 10.
The camera 10 also includes a zoom effect viewfinder arrangement
43 having a secondary lens system 44 and viewfinder 45. The viewfinder
arrangement 43 operates in cooperation with a viewfinder zoom control
algorithm 300, to provide the user with, in another preview mode
of operation, a visualization of the object scene that will be captured.
In this mode of operation, the user is able to visualize the object
scene with no power applied to the LCD unit 38 to effect a significant
increase in the operating period of the camera. In short then, in
this viewfinder preview mode of operation, the LCD unit 38 does
not exert a power drain on the electrical system of the camera 10
as the LCD unit 38 is not placed in a power on condition. A selection
switch 33 allows the user to switch the operating mode of the camera
10 between the two different modes of operation, a viewfinder only
mode and a LCD mode. In order to facilitate zoom in and zoom out
commands, the camera 10 also includes a zoom in switch 30 and a
zoom out switch 32 as best seen in FIG. 1.
A stepper motor 29 coupled between the microprocessor 25 and the
primary and secondary lens systems 14 and 44 respectively, causes
the respective lens systems 14 and 44 to be moved for focusing and
zooming purposes. The stepper motor 29 under the control of the
microprocessor 25 and a fixed focus control algorithm 100 (FIG.
5) incrementally adjusts, for a given aperture setting, the primary
lens system 14 to a predetermined focal pointing setting when the
camera 10 is operating in the fixed focus mode of operation. The
stepper motor 29 under the control of the microprocessor 25 and
the zoom control algorithm 300 also zooms the primary lens system
14 and the secondary lens system 44 over an optical zoom range between
1.times. magnification and 2.times. magnification. At the end of
the optical zoom range, when the primary lens system 14 can no longer
effect any greater zooming effects, the microprocessor 25 causes
the stepper motor 29 to continue to move the secondary lens system
44 in such a manner as to simulate digital zooming effects that
are directly viewable by the user without activating the LCD unit
38. That is, the secondary lens system 44 will continue to magnify
the object scene as viewed in the viewfinder 43, even though the
primary lens system 14 is no longer moving. In short then, the amount
of magnification the optical viewfinder 43 will show is the product
of the optical and digital zoom factors as shown in Table A.
For example, the optical zoom function has an operating range from
about Z.sub.1 to about Z.sub.n which is expressed in a series of
finite steps as Z.sub.1, Z.sub.2, Z.sub.3, . . . Z.sub.n. Thus,
in optical zoom operations, the primary lens system 14 and the secondary
lens system 44 move in tandem along their respective primary and
secondary light paths in a series of continuous finite steps from
Z.sub.1 to Z.sub.n when the user zooms in to obtain a telescopic
object image. Conversely, when the user zooms out to obtain a wide
angle object image, the lens systems 14,44 move in an opposite direction
in a continuous series of finite steps from Z.sub.n to Z.sub.1.
Once the primary lens system 14 has been moved to its maximum optical
zoom position at Z.sub.n, no further optical zoom is possible. In
this regard, if the user desires to continue to zoom in on an object
image, the camera 10 automatically switches to the digital zoom
mode.
In the digital zoom mode there is another series of finite magnification
factor steps as D.sub.1, D.sub.2, D.sub.3, . . . D.sub.n to provide
a range from about D.sub.1 to D.sub.n. In this mode of operation,
the microprocessor 25 causes the CCD 15 to manipulate its output
signal to provide the effects of digital zooming that may be observed
on the LCD unit 38 if the camera is operating in the LCD active
mode. The practical effects of what is viewed on the LCD unit 38
is the product of the current optical zoom factor (for example Z.sub.n)
and the current digital zoom factor (for example D.sub.n) to provide
the overall effective zoom factor of Z.sub.n D.sub.n.
To permit the user to visualize this zooming effect in the viewfinder
45, the microprocessor 25, under the control of a zoom control program
300, causes the secondary lens system 44 to continue movement along
the secondary light path from the maximum optical zoom position
of Z.sub.n to a maximum effective zoom position of Z.sub.n D.sub.n.
In short then, as the secondary lens system 44 travels along the
secondary light path, the lens moves in a series of finite steps
that simulate the optical digital zoom factor products that range
from Z.sub.1 D.sub.1 as a minimum effective zoom product to Z.sub.n
D.sub.n as a maximum effective zoom product.
In the preferred mode of operation, the microprocessor 25, in response
to the zoom in and zoom out signals produced by the zoom in switch
30 and the zoom out switch 32 respectively, calculates the product
of the current optical zoom factor and the current digital zoom
factor to determine the positions that the stepper motor 29 needs
to move the respective primary lens 14 and secondary lens 44. Thus
for example, if the current optical zoom factor position is Z.sub.4
and the current digital zoom factor position is D.sub.2 the microprocessor
25 will cause the secondary lens system 44 to move to a position
that simulates the effective optical digital zoom product of Z.sub.4
D.sub.2.
As mentioned earlier Table A illustrates the effective zoom factors.
TABLE A Effective Optical Digital Zoom Zoom Zoom Product Z1 D1
Z1D1 Z2 D1 Z2D1 Z3 D1 Z3D1 . . . . . . . . . ZN D1 ZND1 ZN D2 ZND2
. . . . . . . . . ZN DN ZNDN
Table B illustrates a series of different effective zoom magnification
factors based on current optical zoom magnification factors and
current digital zoom factors.
TABLE B Optical Digital Effective Zoom Zoom Zoom 1X 1X 1X 1.5X
1X 1.5X 2X 1X 2X 2X 1.5X 3X 2X 2X 4X
From the foregoing, it should be understood by those skilled in
the art that this approach improves ease of use for the user as
the effects of optical zoom and digital zooming can be viewed through
the viewfinder 43 or in the alternative, on the LCD unit 38 if the
user so chooses to activated this device. As a further benefit,
the use of the viewfinder 43 and secondary lens system 44 masks
the need to know when one is optical zooming and digital zooming
which concepts are difficult for the average user to comprehend.
Although in the preferred mode of operation the camera 10 has been
described as including a stepper motor 29 to effect lens movements,
those skilled in the art will appreciate that other forms of motive
means such as ac and dc motors can be utilized to effect such movement.
Thus, there is no intention of limiting the scope of the present
invention to merely a stepper motor.
Although a two-switch arrangement has been shown in the preferred
embodiment of the present invention, it will also be appreciated
by those skilled in the art that different switch arrangements may
be utilized. For example a four to six switch arrangement could
provide separate switches for optical zoom in, optical zoom out,
digital zoom in, digital zoom out, viewfinder mode, LCD mode functions.
As another example a single zoom in zoom out switch could be coupled
with a three-switch arrangement to select an optical zoom mode,
a digital zoom mode and a LCD mode, where the viewfinder mode would
be a default mode. Thus, as many different types and kinds of switches
as well as menu selection functions are contemplated within the
true scope of the present invention there is no intention of limiting
the invention to the switch arrange as shown and described.
From the foregoing, it should be understood by those skilled in
the art that this approach improves ease of use for the user as
the effects of optical zoom and digital zooming can be viewed through
the viewfinder 43 or in the alternative, on the LCD unit 38 if the
user so chooses to activated this device. As a further benefit,
the use of the viewfinder 43 and secondary lens system 44 masks
the need to know when one is optical zooming and digital zooming
which concepts are difficult for the average user to comprehend.
Before describing the zooming features in greater detail it may
be beneficial to review the concepts of optical and digital zooming.
Optical zooming is the traditional method of zooming, where the
primary lens system 14 is moved in such a way that the object of
a scene to be photographed is viewed in a magnified manner via the
LCD unit 38, and thus appears closer to the user in the viewed scene.
Digital zooming is another form of zooming that is only available
in a digital camera. Digital zooming is effected by a series of
steps that include: 1. converting light via a charged coupled device
15 into an electrical analog signal that is indicative of the captured
image; 2. converting the analog signal into a digital signal that
is also indicative of the captured image; 3. coupling the digital
signal to internal microprocessor 25 for storage; 4. processing
zooming commands initiated by the activation of zooming switches,
such as a zoom in switch 30 and a zoom out switch 32; 5. sending
a digital zoom command to the charged coupled device 15; and 6.
converting the digital command into an analog signal via a digital
to analog converter 58 that causes the charged couple device 15
to crop the image capture area so that only a subset of the image
pixels are stored in an available storage or recording medium, such
as on a removable memory card 54 or in an internal memory storage
device 84 as illustrated in FIG. 1.
In this manner, when a non cropped image, one that is derived from
the full image pixel area of the charged couple device 15, and a
cropped image are displayed on the LCD unit 38, the cropped image
will appear magnified-digitally zoomed.
Optical zoom appears smooth in operation as the stepper motor 29
effects movement of the primary lens system 14 in a substantially
continuous fashion in small incremental steps that are masked to
human observation. Digital zooming on the other hand is substantially
different requiring substantial microprocessor time.
In view of the large amounts of microprocessor time required to
implement digital zooming, prior known camera that provide both
optical zoom and digital zoom have integrated the two zooming features
in one of two ways: In a first technique, the camera utilizes optical
zoom until the primary lens system reaches it maximum zoom capability,
and then digital zoom is activated and observed via a LCD unit in
n incremental steps. This approach requires that at least two control
button, one for zoom in and one for zoom out in the digital zoom
mode of operation. In another technique, the optical zoom and the
digital zoom functions are separated so that a user can set the
optical zoom at any setting within its operating range and the set
the digital zoom to any of the n available settings within its range.
The effective zoom is then the product of the optical zoom and the
digital zoom settings. This technique then requires three or four
controls--zoom in, zoom out, and digital zoom which can optionally
be further separated into zoom in and zoom out.
FIG. 6 illustrates in a graphical sense the first technique. In
this regard, it can be seen in FIG. 6 that the zoom coverage is
continuous across the optical zoom range of 38-105. However, a jump
occurs to the 105.times.1.5 or 158 range, and then to the 105.times.2
or 210 range. In short then, with this technique, the user does
not have full use of the zoom range of 38 to 210.
FIG. 7 illustrates in a graphical sense the second technique. In
this approach the zoom coverage is continuous for any zoom setting
between 38 and 210 utilizing both the optical zoom feature and the
digital zoom feature. For example, if the zoom setting of 100 is
considered relative to FIG. 7, it should be obvious to one skilled
in the art that three different approaches can be implemented to
achieve this setting: 1. Optical zoom at 100; 2. Optical zoom at
66 and digital zoom at 1.5.times.; and 3. Optical zoom at 50 and
digital zoom at 2.times..
From the foregoing, it should be understood that the user is provided
with too much flexibility. That is the user is able to compromise
image quality by being too flexible because of the multiple methods
of achieving the same zoom setting. This flexibility is confusing
to a novice user familiar with PAS camera and may lead to a user
lacking a proper understanding of the differences between optical
zooming and digital zooming features.
In order to overcome the problems associated with integrated optical
zoom and digital zoom, the camera 10 only includes two-control switches--a
zoom in switch 30 and a zoom out switch 32. The activation of either
of zoom switches 30 and 32 causes the microprocessor 25 to execute
another zoom control algorithm 1200.
Considering now the zoom control algorithm 1200 in greater detail,
with reference to FIGS. 8 and 12, a set of variables need to be
defined: Z.sub.w =the shortest setting of the optical zoom range.
Z.sub.t =the longest setting of the optical zoom range. D.sub.1
=the first step of the digital zoom range. D.sub.2 =the second step
of the digital zoom range. D.sub.n =the nth step of the digital
zoom range. B.sub.w =the switch or button control for zooming in.
B.sub.t =the switch or button control for zooming out.
The zoom control algorithm 1200 comprises a smooth zoom in operation
1220 and a smooth zoom out operation 1260 that operate in the following
manner in view of the variable definitions set forth above: 1. When
the user activates the zoom out switch B.sub.t the optical zoom
feature is enabled in the optical zoom range of between about Z.sub.w
and about Z.sub.t. 2. When the primary lens system 14 reaches its
maximum zoom range of about Z.sub.t and the user continues to depress
the zoom out switch B.sub.t the algorithm 400 causes the primary
lens system 14 to step back to the point Z.sub.t /D.sub.1 and activates
the first digital zoom step of D.sub.1. 3. As the user continues
to depress the zoom out switch B.sub.t the primary lens system 14
is again advanced until it reaches its maximum range position of
about Z.sub.t while the first digital zoom step of D.sub.1 remain
active. The combined zoom product is thus, Z.sub.t D.sub.1. 4. When
the primary lens system 14 reaches its maximum zoom range of about
Z.sub.t and the user continues to depress the zoom out switch B.sub.t
the algorithm 1200 causes the primary lens system 14 to step back
to the point (Z.sub.t /D.sub.1)/D.sub.2 and activates the second
digital zoom step of D.sub.2. 5. As the user continues to depress
the zoom out switch B.sub.t the primary lens system 14 is again
advanced until its reaches its maximum range of about Z.sub.t while
the second digital zoom step of D.sub.2 remain active. The combined
zoom product is thus, Z.sub.t D.sub.2 /D.sub.3. 6. When the primary
lens system 14 reaches its maximum zoom range of about Z.sub.t and
the user continues to depress the zoom out switch B.sub.t the algorithm
1200 causes the primary lens system 14 to step back to the point
(Z.sub.t /D.sub.2)/D.sub.3 and activates the third digital zoom
step of D.sub.3. 7. The above described advance, backup, advance
steps are repeated until the point of Z.sub.t D.sub.n is reached
which point is the maximum zoom range of the optical zoom and the
digital zoom in combination. 8. When the user depresses the zoom
in switch B.sub.w the algorithm unravels the above-described steps
in reverse order.
From the foregoing, it will be appreciated by those skilled in
the art that the result is a continuous zoom range from Z.sub.w
all the way to Z.sub.t D.sub.n without any gaps in the zoom coverage
as best seen in FIG. 6. This result is achieved with the use of
the standard two-button scheme of a zoom in switch, such as the
zoom in switch 30 and a zoom out switch, such as the zoom out switch
32. In short then, image quality is maximized for every setting
because optical zoom is always used whenever possible over the digital
zoom ranges.
Considering now the zooming features of the camera 10 in still
greater detail, the camera 10 includes a zoom in switch 30 and a
zoom out switch 32 that cooperate with a zoom control algorithm
300 (FIG. 3) to effect a continuous zoom range over both the optical
zoom range and the digital zoom range. In this regard, the optical
zoom is always used whenever possible over the digital zoom.
Considering now the viewfinder zooming algorithm 300 in greater
detail with reference to FIG. 3, the zooming algorithm 300 begins
at a start command 302 whenever power is applied to the camera 10.
The program immediately advances to a command step 304 that sets
the optical zoom factor Z to a default setting of Z.sub.w or 1.times.
magnification and the digital zoom factor D to a default setting
of D.sub.1 or 1.times. magnification causing the primary lens 14
and the secondary lens 44 to be moved to their default positions.
Next the program advances to a determination step 306 to wait for
the primary lens 14 and the secondary lens 44 to be adjusted to
their default positions by the stepper motor 29.
Once the primary lens 14 and the secondary lens 44 have been adjusted
to their default positions, the program proceeds to a determination
step 308 to determine whether or not the user has activated the
zoom in switch 30. If the user has activated the zoom in switch
30, the program goes to a call command 310 that calls a zoom in
subroutine 340 that will be described hereinafter in greater detail.
If the user has not activated the zoom in switch 30, the program
advances to a decision step 312 to determine whether or not the
user has activated the zoom out switch 32. It should be noted that
after the zoom in subroutine 340 has been executed the program then
advances to the decision step 312.
At the determination step 312, if a determination is made that
the user has not activated the zoom out switch 32, the program goes
to a decision step 316 to verify whether or not the user desires
to power down the camera 10. If at the determination step 312 a
determination is made that the user has activated the zoom out switch
32, the program proceeds to a call command 314 that calls a zoom
out subroutine 360 that will be described hereinafter in greater
detail. After the zoom out subroutine 360 has been executed the
program proceeds to the determination step 316 to determine whether
the user has initiated a power camera down sequence.
If the user desires to power down the camera 10, the program goes
to an end step 318 and the camera 10 is powered down. If the user
has not initiated a power down sequence, the program returns to
the determination step 308 and proceeds as previously described.
From the foregoing, it will be understood by those skilled in the
art that the zoom control algorithm 300 will proceeds from steps
308 to 316 to effect zoom in and zoom out operations until such
time as the user desires to power down the camera 10.
Considering now the zoom in subroutine 340 in greater detail with
reference to FIG. 3, when the call command 310 is executed the program
proceeds to a start command at 320 that initiates the zoom in subroutine
340. From the start command 320, the program advances to a command
step 344 that determines and stores the current zoom out range value.
In this regard, the zoom out function has a range from a minimum
combined optical digital zoom factor of Z.sub.w D.sub.1 or Z.sub.1
D.sub.1 to a maximum combined optical digital zoom factor of Z.sub.t
D.sub.n or Z.sub.n D.sub.n.
From step 344, the program proceeds to a decision step 346 to verify
whether or not the current optical digital zoom factor is set to
a maximum value of Z.sub.n D.sub.n. If the current optical digital
zoom factor product is set to a maximum value, the camera system
is in a fully zoom in position and no further telescopic effects
are possible. In this regard, the program proceed to a decision
step 322 to determine whether the user has activated the zoom mode
control switch 33 to place the camera 10 in the LCD mode. If the
user has activated the LCD mode switch 33, the program proceed to
a command step 324 that causes the LCD unit 38 to be powered up.
After the LCD unit 38 has been powered up the program advances to
a call command 348 that calls the subrountine smooth zoom in 1220
that will be described hereinafter in greater detail. If a determination
is made at the decision step 322 that the user has not activated
the LCD mode switch 33, the program proceeds directly to the call
command 348 to call the smooth zoom in subroutine 1220.
Once the smooth zoom in subroutine 1220 has been executed, the
program advances to a return step 349 that returns the program to
the zoom control algorithm by exiting the call step 310 and advancing
to the decision step 312.
Considering now the zoom out subroutine 360 in greater detail with
reference to FIG. 3, when the call command 314 is executed the program
proceeds to a start command at 330 that initiates the zoom out subroutine
360. From the start command 330, the program advances to a command
step 364 that determines and stores the current zoom in range value.
In this regard, the zoom in function has a range from a maximum
combined optical digital zoom factor of Z.sub.t D.sub.n or Z.sub.n
D.sub.n to a minimum combined optical digital zoom factor of Z.sub.w
D.sub.1 or Z.sub.1 D.sub.1.
From step 364, the program proceeds to a decision step 366 to verify
whether or not the current optical digital zoom factor is set to
a minimum value of Z.sub.1 D.sub.1. If the current optical digital
zoom factor product is set to a minimum value, the camera system
is in a fully zoom out position and no further wide angle effects
are possible. In this regard, the program proceed to a decision
step 332 to determine whether the user has activated the zoom mode
control switch 33 to place the camera 10 in the LCD mode. If the
user has activated the LCD mode switch 33, the program proceed to
a command step 334 that causes the LCD unit 38 to be powered up.
After the LCD unit 38 has been powered up the program advances to
a call command 368 that calls the subrountine smooth zoom out 1260
that will be described hereinafter in greater detail. If a determination
is made at the decision step 332 that the user has not activated
the LCD mode switch 33, the program proceeds directly to the call
command 368 to call the smooth zoom out subroutine 1260.
Once the smooth zoom in subroutine 1260 has been executed, the
program advances to a return step 369 that returns the program to
the zoom control algorithm by exiting the call step 314 and advancing
to the decision step 316. The zoom control program 300 then proceeds
as described previously.
From the foregoing it should be understood by those skilled in
the art that the zoom in subroutine 340 increases the zoom magnification
factors so long as the user continues to hold the zoom switch 30
in an increase zooming state. On the other hand, if the user is
attempting to decrease zooming, zoom out subroutine 360 decreases
the zoom magnification factors so long as the user continues to
hold the zoom out switch 32 in a decrease zooming state. In short
then, the user can zoom in or zoom out visualizing the effects of
both optical and digital zooming either using the viewfinder 45
or the LCD 38 depending upon which operating mode the user has selected.
Considering now the smooth zoom in subroutine 1220 in greater detail
with reference to FIG. 12, the subroutine 1220 is entered via the
call command 348 in the zoom control algorithm 300. The subroutine
1220 begins at a start command 1222 and proceeds to a decision step
1224 to determine whether the digital zoom magnification factor
D has been set to a maximum value of D.sub.n. If the digital zoom
magnification factor D has not been set to the maximum value, no
further telescopic zooming is possible, in this regard, the subroutine
proceeds to a return command at step 1225 directing the program
to the zoom in subroutine step 349 where the program proceeds as
described previously. If the digital zoom magnification factor D
has not been set to the maximum value, the program proceeds to a
decision step 1226 to determine whether or not the optical zoom
magnification factor Z is set to its maximum value of Z.sub.t.
If the optical zoom magnification factor Z has not been set to
a maximum value, the smoothing algorithm 1220 causes the primary
lens system 14 to step forward increasing the magnification by one
incremental step via a command step 1250. In this regard, the command
step 1250 causes the primary lens system 14 to move the incremental
step. The program then proceeds to a decision step 1252 to wait
for the primary lens 14 to be advanced. Once the primary lens has
been advanced the program goes to a return step 1254 returning the
program to the zoom in subroutine at step 349 where the program
proceeds as described previously.
If the optical zoom magnification factor Z has been set to a maximum
value any increase in magnification will be caused digitally. In
this regard, the program goes to a command step 1228 from the decision
step 1226 to increase the digital zoom factor by one. To effect
a smooth transition to the new optical digital zoom product, the
program proceeds to a command step 1230 that causes the primary
lens 14 to backoff one incremental step or position. Next the program
proceeds to a decision step 1232 to wait for the primary lens 14
to be adjusted.
Once the primary lens system 14 has been adjusted the program goes
to a decision step 1234 to determine whether the primary lens 14
is positioned at its maximum setting. In this case, since the primary
lens has been back off one incremental step from its maximum setting,
the maximum optical lens position has not been achieved. Thus, the
program proceeds from the decision step 1234 to a return step 1236
causing the program to exit the zoom in subroutine by advancing
to step 349 where the program proceeds as described previously.
If a determination is made at step 1234 that the optical zoom factor
Z is set to a maximum optical magnification setting, the program
advances to a decision step 1238 to determine whether the user has
activated the zoom out switch B.sub.w indicated at 32 in FIG. 1.
If the user has not activated the zoom out switch 32, the program
advances to a return step 1240 that returns the subroutine to the
zoom in algorithm at step 349 where the program proceeds as described
previously.
If a determination is made at decision step 1238 that the user
has activated the zoom out switch 32 so that B.sub.w is set active,
the subroutine goes to a call command 1242 that calls the smooth
zoom out subroutine 1260. From the call command 1242 the smooth
zoom in subroutine 1220 ends at step 1244.
Considering now the smooth zoom out subroutine 1260 in greater
detail, the subroutine 1260 is entered at a start command 1261 from
either the call command 1242 from the smooth zoom in subroutine
1220 or from the zoom out subroutine 360 from the call step 368.
In either event, the program proceeds from the start step 1261 to
a decision step 1262 to determine whether or not the digital zoom
factor D has been set to a maximum magnification value of D.sub.n.
If the digital zoom factor D has not been set to its maximum telescopic
value, the program advances to a decision step 1280 to verify whether
the optical zoom factor has been set to its minimum value of Z.sub.w
or Z.sub.1. If the optical zoom factor Z is set to its minimum value
any further decrease in the magnification of the object scene can
only be effected by decreasing the digital zoom factor D. In this
regard, the subroutine goes to a decision step 1281 to determine
whether the digital zoom factor D has been set to its minimum value
of D.sub.1. If the digital zoom factor D is set to its minimum value,
the combined optical digital zoom product is 1.times. magnification
and no further wide angle zoom is possible since the camera is set
to it minimum wide angle setting. In this regard, the program proceeds
to a return step 1283 that returns the program to the zoom control
algorithm 300 at step 369 where the program continues as described
previously.
If a determination is made at step 1281 that the digital zoom factor
D is not set to its minimum value of D.sub.1, the program goes to
a command instruction 1282 that decrements the digital zoom factor
by one incremental step. In order to smooth the transition from
the one digital setting to the other, the program advances to a
command step 1284 that increases the optical zoom factor setting
by one incremental step while instructing the stepper motor 39 to
advance the primary lens position one incremental step. The program
then proceeds to a decision step 1286 to wait for the primary lens
14 to move to its new position.
After the primary lens 14 has moved to its new position, the program
goes to a decision step 1287 to determine whether the optical zoom
factor has been set to a minimum setting. In this case, since the
optical zoom factor has just been incremented from its minimum setting
the program goes to a return step 1289 that returns the subroutine
to the zoom out subroutine at step 369 where the program proceeds
as described previously.
If at decision step 1287 it is determined that the optical zoom
factor has not been set to a minimum setting, the program advances
to a decision step 1291 to determine whether the user has activated
the zoom in switch B.sub.t indicated at 30 in FIG. 1. If the zoom
in switch 30 has been activated so B.sub.t =1, the program goes
to a call command 1293 that calls the smooth zoom in subroutine
1220 causing the program to advance to the start command 1222 as
described previously.
If the zoom in switch 30 is not active, the program proceeds to
a return command 1297 advancing the subroutine to the zoom out subroutine
360 at step 369 as described previously.
Considering again the decision step 1280 if a determination is
made that the optical zoom factor Z is not set to a minimum value
of Z.sub.1 the optical zoom can be decreased by an incremental step.
In this regard, the program proceeds to a command step 1288 that
decreases the optical zoom factor by one increment and causes the
stepper motor 39 to move the primary lens 14. The program then advances
to a decision step 1292 to wait for the primary lens system 14 to
be adjusted.
Once the primary lens system 14 has been adjusted, the program
proceeds from step 1292 a decision step 1294 to determine whether
the user has activated the zoom in switch B.sub.t indicated at 30
in FIG. 1. If the user has not activated the zoom in switch 30,
the program return to the zoom out subroutine 360 executing a return
step 1298. Conversely, if the user has activated the zoom in switch
30, the program advances to the call step 1297 and proceeds as described
previously.
Considering now the focusing of the camera 10 in greater detail
with reference to FIG. 1, the camera 10 includes a fixed focus mode
of operation as well as an automatic focus mode of operation. In
the fixed focus mode, the camera 10 as will be explained hereinafter
in greater detail automatically adjusts its focal point and aperture
setting relative to the amount of ambient light being received through
the primary lens system 14 of the camera 10.
In order to facilitate the fixed focus mode and the automatic focus
modes of operation, the camera 10 includes the adjustable aperture
18 that cooperates with the primary lens arrangement 14 and the
shutter 19 for admitting light to the charged couple device 15 for
a predetermined period of time. The charged couple device 15 converts
the light that is received into an electrical signal that is indicative
of an object to be photographed as well as the ambient light conditions
surrounding the object.
An analog to digital converter 56 converts the electrical signal
generated by the charged couple device 15 into a digital signal
that is coupled to the microprocessor 25. The microprocessor 25
through various ones of the algorithms embodied therein, as will
be explained hereinafter in greater detail, automatically places
the camera 10 in the fixed mode of operation upon the camera being
activated. The microprocessor 25 also causes the aperture 18 of
the camera 10 to be adjusted to an optimal setting and then automatically
adjusts the focal point of the camera 10 to facilitate ease of use
by the camera user. More specifically these automatic adjustments
and setting are achieved through an a fixed focus mode algorithm
100 (FIG. 5), an automatic focus mode algorithm 200 (FIG. 11) and
an aperture control algorithm 400, (FIG. 4) each of which, will
be described hereinafter in greater detail.
Considering now the fixed focus mode algorithm 100 in greater detail
with reference to FIG. 5, the fixed focus mode algorithm 100 is
responsive to the optimal setting of the aperture 18 as determined
by the aperture control algorithm 400, and automatically moves the
primary lens system 14 to a predetermined focal point. In the fixed
focus mode of operation, the following operational steps are achieved:
1. The algorithm 100 causes the shutter 19 to be opened allowing
the microprocessor 25 to receive a digital signal indicative of
the ambient lighting conditions. 2. The algorithm 100 based on the
determined ambient lighting conditions determines an appropriate
shutter speed and aperture size for facilitating the capturing of
a properly exposed image object. 3. The algorithm 100 based on the
determined aperture size causes the primary lens 14 to be moved
to a predetermined focal point for proper focusing of the image
object to be captured. Each aperture size has a corresponding focal
point. Thus, since there are three different aperture size settings
there are three corresponding focal point settings in the fixed
focus mode of operation. A look up table stored in the internal
memory storage device 84 is accessed by microprocessor 25 so that
it retrieves a proper focal point setting based upon the aperture
size determined by the algorithm 400. Since the camera 10 has the
capability of using aperture size to maximize the range within which
an object is located, and still be in focus the camera 10 is referred
to as "aperture sensitive". This is an important feature
of the camera 10 as the fixed focus mode of operation is the default
mode. Such a default mode saves a substantial amount of time in
comparison to prior art cameras that power up in an automatic focus
mode, as only one primary lens movement is required.
Considering now the fixed focus mode algorithm 100 in still greater
detail with reference to FIG. 5, the fixed focus mode algorithm
100 begins at a start command 102 when power is applied to the camera
10. The program then proceeds to a command instruction 104 that
places the camera 10 in the fixed focus mode of operation changing
the focus switch 31 from its normally neutral position to a fixed
focus mode setting indicated at 26.
From the command instruction 104 the program goes to a determination
step 105 to wait for the user to activate the shutter button 36
to a 1/2 way position to initiate an adjustment. The program advances
from step 105 to a command step 106 when the shutter button 36 has
been depressed to the adjust position. Step 106 causes the shutter
19 to be fully opened exposing the CCD 15 to the ambient lighting
conditions via the primary lens system 14. Once the microprocessor
25 receives the digital signal indicative of the ambient lighting
conditions, the program advances to a call command step 108 that
calls the algorithm 400 that calculates a proper aperture setting
and shutter speed based upon the strength of the ambient light signal
received by the microprocessor 25. The aperture shutter speed control
algorithm 400 will be discussed hereinafter in greater detail.
After the aperture setting and shutter speed has been determined
by reference to a simple look up table, via the algorithm 400, the
program returns to the fixed focus mode algorithm at a command step
110 that causes the stepper motor 29 to adjust the size of the aperture
to a determined one of its three primary aperture settings indicated
at 20,21, and 22 respectively. The program then proceeds to a determination
step 112 to verify that the aperture 18 has been set to its proper
setting.
Once the aperture 18 has been adjusted, the program proceeds to
a command step 116 that retrieves from a look up table in the internal
memory 84 a focal point setting. From the command step 116 the program
advances to a command step 118 that causes the stepper motor 29
to move the primary lens system 14 to the retrieve focal point setting.
The program goes to a determination step 120 that determines whether
the lens 14 has been adjusted. Once the lens focal point is set,
the program proceeds to an end command 122.
Considering now the automatic focus mode algorithm 200 in greater
detail with reference to FIG. 11, in order to place the camera 10
in the automatic focus mode of operation, the user toggles the focus
from its normally fixed focus position at 26 to an automatic focus
mode setting indicated at 28. Once the camera 10 is placed in the
automatic focus mode, the user is free to depress a shutter release
button or switch 34 to an initial half way stop position for generating
an electrical signal that causes the microprocessor 25 to execute
the automatic focus mode algorithm 200. In the automatic focus mode
of operation, the following operational steps are achieved while
the shutter release button is disposed at its initial half way stop
position: 1. The algorithm 200 causes the shutter 19 to be opened
allowing the microprocessor 25 to receive a digital signal indicative
of the ambient lighting conditions. 2. The algorithm 200 causes
the LCD 38 to provide a new indication to the user, such as a blinking
indication, that the primary lens system 14 has been adjusted to
the proper focal point. Once the user sees this new indication,
the shutter release button 34 may be fully depressed resulting in
the capturing and storing of a digital image in proper focus.
The setting determined in the above described procedure are maintained
for subsequent shutter actuation to facilitate ease of use by the
user.
Considering now the auto focus mode algorithm 200 in still greater
detail with reference to FIG. 11, the auto focus mode algorithm
200 begins at a start command 202 when power is applied to the camera
10. The program then proceeds to a determination step 204 to detect
whether the user has activated the focus switch 31 to place the
camera in the auto focus mode of operation. In this regard, the
program loops at the determination step 204 until the user activates
the toggle switch 31 to place the camera in the auto focus mode.
From the determination step 204 the program proceeds a determination
step 206 to wait for the user to depress the shutter button 34 to
its half way stop point. When the user depresses the shutter button
34 to its half way stop point, the program advances to a command
step 208 that causes the shutter 19 to be fully opened exposing
the CCD 15 to the ambient lighting conditions via the primary lens
system 14. Once the microprocessor 25 receives the digital signal
indicative of the ambient lighting conditions, the program advances
to a call command step 210 that calls the algorithm 400 that determines
a shutter speed and proper aperture setting based upon the strength
of the ambient light signal received by the microprocessor 25.
After the aperture setting and shutter speed has been determined
in algorithm 400, the program returns to the auto focus mode algorithm
200 at a command step 212 that causes the stepper motor 29 to close
the shutter 19 and to adjust the size of the aperture to the determined
one of its three primary aperture settings indicated at 20,21, and
22 respectively. The program then proceeds to a determination step
214 to verify that the aperture 18 has been set to its proper setting.
Once the aperture 18 has been adjusted, the program proceeds to
a command step 216 that calculates a proper shutter speed for the
determined aperture setting. The shutter speed is stored in the
internal memory 84 of the microprocessor. The program then advances
to a call step 218 that calculates a focal point position for the
primary lens 14 based upon the amount of ambient light being received
by the CCD 15. This determination is made so the CCD 15 will receive
the maximum amount of light possible based on the current ambient
light conditions. The algorithm that calculates the focal point
position is well known to those skilled in the art and will not
be described hereinafter in greater detail. The program then goes
to a command step 220 that causes the stepper motor 29 to advance
the lens system 14 to the determined position.
Next the program proceeds to a determination step 222 to wait for
the lens system 14 to be moved to its proper position. Once the
lens system 14 has been adjusted the program goes to a command step
224 that causes the LCD unit 38 to blink at a desired blink frequency
to provide the user with an indication that the lens system 14 has
been adjusted and that the camera is now in a ready state for a
photograph to be taken.
The program then goes to a determination step 226 to wait for the
user to fully depress the shutter button 34. In this regard, when
the user fully depresses the shutter button 34 the program advances
from the determination step 226 to an activate command 228 that
activates the shutter 19 at the determined shutter speed to expose
the CCD 15.
The program then goes to a determination step 230 to verify whether
or not the user has activated the focus switch 31 to change the
camera back to the fixed focus mode of operation. If it is determined
that the user has changed the mode of operation, the program proceeds
to the fixed focus mode algorithm 100 at the command 105 where the
program proceeds as described previously.
If a determination is made at step 230 that the user desires to
continue operating in the auto focus mode of operation, the program
goes to a determination step 234 to determine when the user desires
to power down the camera 10. If the user desires to power down the
camera 10, the program advances to an end step 236 to exit the auto
focus algorithm 200. If the user does not desire to power down the
camera, the program goes to a go to step 238 that returns to the
determination step 206 to wait for the user to again depress the
shutter button 34. In this manner, the camera remains adjusted for
continuous shooting of additional images until the user either changes
the auto focus mode to the fixed focus mode or the camera is powered
down to an off power condition.
Considering now the aperture control algorithm 400 in greater detail,
the aperture control algorithm is responsive to the digital signal
provided through the analog to digital converter 56 an automatically
adjusts the aperture 18 to an optimal setting relative to the amount
of ambient light conditions surrounding the object to be photographed.
In this regard, the algorithm 400 is entered at a start command
402 (FIG. 4) from either the call command 108 in the fixed focus
mode algorithm 100 or the call command 216 in the auto focus mode
algorithm 200. The program then proceeds to a command 404 that determines
the proper aperture setting for the given or measured ambient light
conditions.
Once the proper aperture setting has been determined at step 404,
the program goes to another determination step 405 to determine
a shutter speed base on the determined aperture setting. The program
then advances to a move command at step 406 that causes the stepper
motor 29 to move the aperture 18 to one of its three primary positions
as best seen in FIG. 9. The aperture settings are conventional camera
settings of 2.8, 5.6, and 11 which settings are indicated generally
at 20,21 and 22 respectively. The program then goes to a return
step 408 that returns the program to the active focus control 100
or 200 depending upon which focus mode the camera 10 was set to
operate. If the camera is operating in the fixed mode the program
advances to step 110, in the fixed focus mode algorithm 100, otherwise
the program advances to step 212 in the auto focus algorithm 200.
Referring now to the drawings and more particularly to FIG. 13,
there is shown a digital camera 1310 which is constructed in accordance
with the present invention. The digital camera 1310 is substantially
similar to the camera 10 except the camera 1310 includes an image
resolution switch 1320 for permitting the user to select one of
a plurality of different image resolutions or file sizes as indicated
in Table C:
TABLE C File Size Without Digital Zoom 1600 .times. 1200 1280 .times.
960 1024 .times. 768 640 .times. 480
The different image resolution selections as indicated in Table
C allows the user to make a tradeoff between file size and image
quality.
As best seen in FIG. 13, the digital camera 1310 also includes
a microprocessor 1325 that is responsive to an enhanced digital
zoom control algorithm 1400. The enhanced digital zoom control algorithm
1400 as will be explained hereinafter in greater detail, compares
a set of resolution pixel values in a generated image file with
corresponding ones of resolution pixel values in a user selected
file to determine which one of the files has the greater settings.
The control algorithm then provides as a final digital zoom image
resolution using the set of resolution pixel values in the generated
image file when the corresponding ones of the resolution pixel values
in the user selected file are at least equal to but not less than
the corresponding resolution pixel values in the generated image
file, and a scaled down set of resolution pixel values when the
corresponding ones of the resolution pixel values in the user selected
files are less than the corresponding resolution pixel values in
the generated image file.
Before discussing the algorithm 1400 in greater detail, it may
be beneficial to review once again the traditional operation of
digital zoom. In this regard, when digital zoom is applied to a
captured image, the traditional zoom control crops the captured
image and causes the image to be displayed in the current resolution
setting of the camera. Thus, for example, if a 1.5.times. digital
zoom factor was selected by a user using a 1024 by 768 resolution
setting, a captured image would be stored in factored file size
of 1024/1.5 locations by 768/1.5 locations to provide an image having
a resolution of 682 pixels by 512 pixels. Table D summarizes the
resulting file sizes for 1.5.times. and 2.0.times. digital zoom
in a traditional digital camera.
TABLE D File Size w/o File Size with File Size with Digital Zoom
Effect 1.5x Digital Zoom Effect 2.0x Digital Zoom Effect 1600 .times.
1200 1066 .times. 800 800 .times. 600 1280 .times. 960 853 .times.
640 640 .times. 480 1024 .times. 768 682 .times. 512 512 .times.
384 640 .times. 480 426 .times. 306 320 .times. 240
From Table D, those skilled in the art will understand that even
though a user may have set the camera resolution to a 1280 by 960
resolution mode, the camera will only deliver an image of VGA quality
or 640 pixels by 480 pixels when the camera is operated with a 2.0.times.
digital zoom effect. As will be explained hereinafter in greater
detail, the enhanced digital zoom feature of the camera 310 provides
a substantially improved image resolution over such a traditional
camera.
Considering now the enhanced digital zoom feature algorithm 1400
in greater detail, the algorithm 1400 begins at a start command
1402 and advances to a store command 1404 that causes the zoom factor
setting Z.sub.f selected by the user to be stored. In the present
embodiment, the camera 1310 has two zoom factor setting: Z.sub.f1
=1.5.times. zoom and Z.sub.f2 =2.0.times. zoom. Although the camera
1310 has only two zoom factor settings, it is contemplated that
the camera 1310 could have a large number of different zoom factors
selected from the following group of zoom factors: 1.25.times.,
1.75.times., 2.25.times., 2.75.times., 3.0.times., 3.25.times.,
3.5.times., 3.75.times., 4.0.times., . . . Z.sub.fn.
After the storing the user selected zoom factor, the algorithm
proceeds to a store command 1406 that causes the image resolution
setting N.sub.sn by M.sub.rn selected by the user to be stored.
In the present embodiment, the camera 1310 has four available resolution
settings where the highest available image resolution value is 1600
pixels.times.1200 pixels as best seen in Table D. Although the camera
1310 has only four available resolution settings, it is contemplated
that the camera 1310 could have a large number of different resolution
settings where the highest available image resolution value is expressed
as a resolution of N.sub.max pixels by M.sub.max pixels.
The algorithm 1400 proceeds to a calculate command 1408 that applies
the user selected zoom factor Z.sub.f to the highest available image
resolution value in the camera 1310, such as the resolution value
of N.sub.max pixels by M.sub.max pixels to obtain a maximum image
file size of N.sub.max /Z.sub.f pixels by M.sub.max /Z.sub.f pixels.
Thus for example, if the highest available camera image resolution
value is 1600 pixels by 1200 pixels, with a user selected 1.5.times.
digital zoom factor, the algorithm 1400 would apply the zoom factor
to generate a resulting file size given by the following calculations:
The algorithm 1400 then proceeds to a compare command 1410 to compare
the generated file size with the user selected file size. The algorithm
then proceeds to a decision step 1412 to determine whether the file
size generated in step 1408 is greater than the user selected image
resolution or file size (N.sub.sn by M.sub.rn) selected by the user
and stored previously at step 1406. Thus for example, if the user
selected an image resolution of 1024 pixels by 768 pixels, the algorithm
would compare the generated file size of 1066.times.800 with the
selected file size of 1024 by 768.
If a determination is made that the calculated set of resolution
pixel values in the generated image file (e.g. 1066.times.800) is
smaller or equal in both dimensions to the size of the user selected
image resolution file (1024.times.768 for this example), the algorithm
1400 proceeds to a select command 1418 that provides as a final
digital zoom image resolution, the user selected image resolution
value. The algorithm then advances to a go to command at 1420 terminating
at an end command 1416.
If a determination is made that the file size that resulted from
the calculate step 1408 exceeds the file size selected by the user
in either dimension (as it does in the present example) then the
image resolution is resized a command step 1414 by a factor of the
larger of the following: [(N.sub.max /Z.sub.f pixels divided by
N.sub.sn pixels) pixels divided into N.sub.max /Z.sub.f pixels]
or 1066/1024=1.04; [(M.sub.max /Z.sub.f pixels divided by M.sub.rn
pixels) pixels divided into M.sub.max /Z.sub.f pixels] or 800/768=1.04.
Since the reduction factors in the present example are the same,
the captured image stored in camera memory system 1384 is resized
while in memory so that the dimensions that exceeds the selected
size become equal. Thus, the captured image is scaled down by the
scaling factor of 1.04 to provide a final digital zoom image resolution
determined as follows:
The algorithm the n proceeds to the end command 1416.
Table E summarizes the resulting file sizes for the 1.5.times.
digital zoom factor and the 2.0.times. digital zoom factor.
TABLE E Enhanced Digital Zoom Image Resolutions File Size Without
File Size With File Size With Digital Zoom 1.5x Digital Zoom 2.0x
Digital Zoom 1600 .times. 1200 1066 .times. 800 800 .times. 600
1280 .times. 960 1066 .times. 800 800 .times. 600 1024 .times. 768
1024 .times. 768 800 .times. 600 640 .times. 480 640 .times. 480
640 .times. 480
As will be noted by comparing Table D with Table E, for all image
size selections above the highest available image resolution of
1600 pixels by 1200 pixels, the enhanced digital zoom control algorithm
1400 provides a higher resolution to the user, the maximizing the
image quality of the resulting image.
While particular embodiments of the present invention have been
disclosed, it is to be understood that various different modifications
are possible and are contemplated within the true spirit and scope
of the appended claims. There is no intention, therefore, of limitations
to the exact abstract or disclosure herein presented. |